Ohio Rev. Code § 2111.09: Administrator or executor ineligible to be appointed guardian.

Unless expressly appointed or designated to act both as guardian and executor by a will in writing, no person who is or has been an administrator or executor of a will shall, prior to the approval of the person's final account as executor or administrator, be appointed a guardian of the person and estate or of the estate only of a ward who is interested in the estate administered upon or entitled to an interest under the will, except that a surviving spouse may be executor or administrator of the deceased spouse's estate and also guardian of the person and estate or of the estate only of a minor child of the surviving spouse, whether or not the minor child is interested in the estate of the deceased spouse. However, an executor or an administrator may be appointed a guardian of the person only of a ward.